isaacson



Sept. 7, 1943.

L. H. ISAACSON GEOMETRICAL INSTRUMENT Filed Nov. 2'7, 1942 2 Sheets-Sheet l INVENTOR L.H .ISAACSON AT ORNEYYS L. H. ISA'ACSON GEOMETRICAL INSTRUMENT Sept. 7, 1943.

Filed Nov. 2'7, 1942 2 She ets-Sheet- 2 INVENTOR H.ISAACSON ,throughout the severalyiews.

of the pivot leg I0. w w a Needle-point assemblies which are designated 1 in' the drawing by the numerals'M and are mounted on bothjthebase 6 and the lever 1 by "press or shrink fits through bosses l6.' Figure 3 shows a verticals'ectionof thebase needle-point jassembly [4, which consists of acentral shaft ll, provided with a needle-point l8 at the lower end and extending upward through-a sleeve I9toen :Appliea mn a m'en e svapp casn5 s; w mega ne a March 331883; asamended by "theaetror 'April 30,;19 23, andfthe invention iherein 'described, ifpatented, may be manufactured-arid; used jby or.

the Gdverrimntfidftht; unit ig states r m 'riea for govern 'eri'tal purposes w'ithoutthe a 1 paymentto me at any royaltythereonQf viide an in;

object or m inventiomis o;

"photographs." y

ure distances betweenjiselected points aeii zoffffiigurdl;

aisaplan assembly {34, showing the tonthe lev er 1; andbj a r V 7 Figure :5: is a side elevation of the same. i

Similar numerals refer to similar Vparts tiewm iaisvsm a v method of attachment a w i The embodiment illustrated in the drawings 1 gcomprises a base 6 and a lever 1. Thebasefi is supported by three legs B, heldin placewith countersunk screws 9, and by a pivot leg l0 hav i ing a roller Hat its lower. endto provid'e rolling 1 {contact at this point of support. Thepivot leg Innis fixed inthe base Gaby a pressforshrink fit win the boss l 2, and extends upwardlyythrough i the base 6 to also act as a p'iyot'for thelever 1.

Anut I3, tapped to allow free movement of the lever'l, engages screw threads on the upper end gage tapped threads'in acap 20-haying a tubular asaasra 130M rsit s rssmamsa y mantaa, 1 am a w-am. a Q n y d rias" w I My.'inye'ntion relates to geometrical Tmezits. Y

strumerit which will api s;aneactu atlyiineasa around the'cent *isgprovided bylaninverted 'lr s lot 'is inthesleeve #9 Iandya small I screw 24 {which passes I through ot- 23-"and engages the-tubular-por on "2 l a a, vn'a in vt tf r o t h te e q spring "2 2"; The lever needle-point assembly J5 is *pointslti 3116,}?1 The scale *33 ean be-iielineated suitable backing and mounted on the base 6. Thearrangement of the scale 33 on both faces of ,be taken-fromtwodirections so thatxthe in-' strument ,can be operated by one person alone,

4 0 and extend to seven inches,a scale marking being marking, and inches are designated by a numeral andtenths of an inch are marked 10, 20, 30,

1 adaptation to particular purposes. a 1 I To obtain readings on the scale 33; a Vernier magnifier assembly 34 is; attached to the underside ofthelever l by countersunk screws 35. The Vernier magnifier assembly 341s composed of two magnifying lenses 36, having hair line indicators,

mtgdo ward-amass receiv s .SlIIlilar ineonstruction, except *thfithe-tnsioh y springflzjisreplacedcbyraoompressionspring 25 Bandactin y g 2 8atdho1d the 20 needlefnointHyieldingIy inan upwardposition;

instead of mates; 2%; a vei-tma1 'slo't an in"thetubularqpfortionfifl 6f the {lap -28, limits" the-action f the-conipressienspiihg-flibutsal a I baseflifin -sulcha an, I "ner that areadingnndicatediby"thelever f1 will be ameasure dfrthe:distancebetweentheneedle directly ontthebase-tyoritrczin*be plaeed on a v the are portion of the base 6 allows reading to" or one person can record readingsywhile another sets the instrument. As illustrated in the draw ing, calibrations on the scale 33 beginat one inch,v

. provided for each interval of one-hundredthfof an inch. Inchestenthsofan inch and fivee hundredths of an inch are distinguished by] a difference inlength of the corresponding scale i and so forth. The calibration and rangeof the scale 33can, of course, beotherwise arranged for t and a frame'3' l. The frame 31'carries-the lenses 3B, and is shapedto the -formof the arc portion of the base ii, so that each lens 36 is in a position to give readings on a respective face of the scale 33.

.The embodiment of my invention set forth above is particularly adapted for use with aerial photographs, where it is desired to measure dis-,

tances from ai-centeripoint to a number of se-' lected points in the outerarea of the photograph. To accomplish this result, the photograph isplaced underthe roller H of the pivot leg it) in I V such a position that the center point will coincidewith the needle-point l8 when-it i'sreleased to its full downward position; The roller H will allow the photograph to be'r'otated'around the needle-point l8, so that the photograph and the lever i can then be adjusted to bring the needlemeans for supporting said base on a plane surface, a pointed element attached to said base,-a

lever pivoted on said base, a pointed element attached to said lever, means for vertically mov-' ing said last-mentioned pointed element in and l out of contact with the plane surface, yieldable means. urgm saidlast-mentioned pointed eleament upward out of contact with-the. plane su1f. face, and a circular scale on said base adjacent to said lever, the radial center of said scale being" coincident with the pivot of said lever.

3. A measuring instrument comprising a base, means for supporting said base on a plane surface, a pointed element attached to said base,

a lever'pivoted on said base, said supporting I means including a post adjacent to the pivot point 29 in line with any oneof the selected points I I in the outer area. When needle pointflfl is depressed to coincide with a selected point, the distance between that point and the center point of; the photograph is the same as between the needle-points I8 and 29, and a reading on the' scale 33 is a measure OfyllhH/D distance- The needle-point EElisthen allowed ltoassume} its upward position,, and the procedure is repeated to bring a second point'into line, and soy on. Whe1 the measuring has been completed, the

dle point I8 islocked inits upward position, I

@allowi ngthe photograph to removed l Use oflmyinvention has provideda considerable saving of time in measuring aerial photo graphs. I It is not,'however, restricted to f.such use, but may be adapted generally to'the'measurement cf ldist'ance.

tosaid lever, and acircular scale on said base "adjacenttosaid lever, the radial center of said scale being coincident with the pivotof said lever.

2. A measuring instrument comprising a base,

- said scale being coincident ,with'theipivot of said lever, said scale being'calibrated'in accordance with theratio .of movement between that part i of said lever to which it is adjacent and said lastofsaid lever and a roller on said post to contact the plane surface, a pointed element attached to saidlever," and a circular scale on said base ad,ia'

cent to said lever, the radial center of said scale I being coincident with the pivot of said lever.

I 4. A measuring instrument comprising ab se,

mean rer' supporting said baseon a plane 5 r,-

face,..a pointed element attached to said bse,

means 'for vertically moving the pointed elem ntf .relative to said base, yieldable means urging said pointed element downward to contact the plane surface, means for holding said pointed element out of contact with the plane surface against the action of saidyieldabl e means, a lever pivoted .onsaidbase, said supporting means including a post adjacent to the pivot of said lever and a.

roller on said post to contact the plane surface,

a pointed elementattached'to said lever, means for vertically moving saidlast-mentioned pointed element in and out of contact with the plane surface, yieldable means urgingsaid last-menftioned pointed-element upward out of contact I with the planesurface, a circular scale on said base adjacent to said lever, the radial center. of

mentioned pointed element, and an indicator attached to said lever adjacent to. said scale,

whereby the position of the adjacent portion of vsaidle'ver with respect to said scalejis defined.

LELAND-ll 'sA osoN; Q 

